Hello
Very frustrating day I’m having. I know that there is a learning curve to this CNC stuff but i thought I would be safe using the file I down loaded from avid. I went to cut the pockets and slots to screw the board down and all the rows turned out fine except the back box was off. I installed my cross bars correctly at 14 1/4" as the 3 other rows of hole fit fine. MDF is costly and don’t want to waste another 25 bucks. Did any one else have this problem?
When I built my avid, I realized their instructions ended up with the crossbeams every 400 mm on center, so I installed them based on that (measured from one end) instead of using a spacer (I hate accumulating errors like that). I wonder if the plans were based on a 400mm spacing - assuming 14 1/4 would add 2mm of error for each crossbeam.
I went out and measured with a metric tape and mine is good at 420,820.1220 from the center of the first cross member.
Are you measuring center to center, or center to left edge? I set zero to be the end of the table, and put the left edge of each piece at 400’s (0, 400, 800, 1200)
From the front edge is 20,420.820,1220 to all the slot centers. Again this is my first CNC and I know nothing about nothing yet. Looking at the drawing in vectric it all seems correct to me measuring the center to center of the slots. When measure from the front rail to the back rail out side to out side its 48 3/4". I think I’m going to try to start from scratch with a new file as I need the practice with V carve. I’m sure it will take me a bit to get it done. (LIKE DAYS).
Ok I’m really confused now. I started from scratch will a new spoil board. I used mm as it was easier to enter the exact location of the rows starting from the front edge. I made sure a changed it in mach 4 also. I did 20, 42 0,820, 1220. I made sure my MDF was flush with the front edge used the touch plate on the left front corner and zeroed it. Ran the tool path and again the last row is off. This time it went long. It’s about 5 mm too far. I just don’t understand if I picked the center of the pocket at 1220 and it went 1225 but the other rows are almost perfect. very strange to me. Please let me know your thoughts. Thanks
I did some measurements and it seems most of my rows are off by about 4-5 mm. Could it be the touch plate? Is there a set up procedure for it? Thanks
I think I might have found my problem after watching a video from Mark Lindsay. I had the bit still at .5 in the touch plate setting not the .25. Not sure if that would be the problem child. Going to re run it again.
And remember to actually measure your bit. They are never what they are claimed.
I know you already know that so you got out your calipers instead of adding the 0.25" value in there 
Yep lesson learned, Im sure many more to come yet. Heading to Lowes now to get a new sheet of MDF. Another 55 bucks.
Be glad you aren’t buying a 61 in x 121 in MDF. A lot more that 55 bucks, if you can find one .
Just don’t worry about the holes at the wrong spot…they won’t be a big deal at all. Just make them at the right spot.
If you are doing two sheets of MDF then it won’t matter at all. You can drop down your first sheet, screw on some t-tracks, and then add slats over the other sheet in-between the t-tracks. (ideally overlapping over the t-tracks for more strength)
Corbin